The present invention relates to a programmer control for a plurality of devices. More particularly, it relates to a programmer control for a plurality of slide projectors and associated audio-visual devices.
In recent years, audio-visual performances using multiple slide projectors and other audio-visual aids have become so complex that an electronic means for arranging the projection sequences has become a necessity. Such an electronic means is hereinafter referred to as a programmer.
Basically, a programmer is a special purpose computer; it serves as a memory storage and retrieval unit for controlling the sequence of operation of a plurality of slide projectors and other audio-visual devices. A good example of such a programmer is the UAV Cuemaster Mark 60 programmer manufactured by United Audio-Visual Corporation.
In general, the operation of the programmer is determined by a punched tape which serves as the memory storage facility. Typically, the punched tape may be an eight channel tape which is one inch wide and composed of paper, plastic film or combinations thereof. The eight channel tape contains the program which determines the sequence of operation of eight slide projectors or other audio-visual devices, and it is provided with one or more holes on each line across the width of the tape. Each of the holes corresponds to a data channel which is connected to a particular audio-visual device. The data may serve to actuate a projector, a dissolve unit, a light, a tape recorder, and so forth.
The tape is fed through an electro-optical tape reader which reads the information on the tape, line by line, and feeds the information to signal processing circuitry in the programmer. The signal processing circuitry receives the tape reader outputs and generates appropriate electronic signals for controlling the audio-visual devices in accordance with the information on the tape. Therefore, each line of holes on the tape corresponds to a particular state or condition of the audio-visual devices. A series of lines, then, corresponds to a sequence of operations of the audio-visual devices or, in other words, a program.
Any number of holes up to eight may be punched on a particular line on the tape, and the particular holes punched will be determined by the particular audio-visual devices which are to be operated at a given instant of time during a performance. Each line on the tape corresponds to a particular instant of time in the audio-visual performance. At each such instant of time, the audio-visual devices may be cued, that is, the state or condition of the audio-visual devices may be changed. As a result, a line on the punched tape may be termed a "cue". Thus, the totality of lines or cues on the tape carries the necessary information for controlling the sequence of operation of the eight audio-visual devices over the time interval of a complete performance.
Although each cue on the tape contains the necessary information for determining the state of particular audio-visual devices at a given instant of time, it may be required that a particular operating state be maintained for a predetermined interval of time without altering the states of any of the audio-visual devices. In that case, a series of cues on the tape will not be punched and, accordingly, the tape reader will scan these cues without generating any electronic signals at the input of the signal processing circuitry. The audio-visual devices, therefore, will not change their states until a cue is reached which contains one or more punched holes.
A programmer such as the UAV Cuemaster has the ability to read an eight hole punched tape at different speeds. At normal speed, the tape reader will read a cue on the tape, proceed to the next cue and then stop. The tape reader will not read the cue to which it has advanced until commanded to do so by a manually operated switch.
In addition, the tape reader may be made to advance and read successive cues automatically. For example, in the UAV Cuemaster, the tape reader may automatically scan the tape at 20 or 60 cues per second. These are called the high speed modes. In the high speed modes, the capacity of the system is limited somewhat because the eighth channel on the tape is no longer used to control a particular audio-visual device. Instead, the eighth channel is used to provide a stop command which serves to stop the reader from advancing further after it has automatically scanned a designated number of cues. Thus, the system capacity is limited to seven channels.
The capacity of the prior art programmer is therefore severely limited. Thus, in the normal mode of operation, the tape reader advances by single cues in response to manually initiated commands, and each channel on the tape corresponds to one of the eight audio-visual devices. In the high speed modes, the tape reader automatically scans the tape at the rates of 20 or 60 cues per second, and only seven of the eight channels correspond to audio-visual devices, the eighth channel being used for the stop command. Accordingly, depending upon the mode of operation of the tape reader, a maximum of either seven or eight audio-visual devices can be controlled by a single programmer.
In order to increase the capacity of the system that is, the number of audio-visual devices that can be controlled by the programmer it is necessary to connect a plurality of programmers in series. Thus for example, five programmers may be connected in series to provide the capacity for operating 40 audio-visual devices. This, however, is a costly and cumbersome procedure which increases the opportunity for operator error since the programmers must be manually adjusted to operate in identical modes.
A principal advantage of the present invention is that, using a standard eight channel punched tape, at least 40 audio-visual devices may be controlled by means of a single tape reader and a single programmer.
A further advantage of the present invention is that the capacity of a programmer is increased in an economical manner without incurring any loss in performance time otherwise arising from the manual adjustment of a plurality of series connected programmers.
Other advantages appear in the description of the invention hereinafter.